1. Field of the Invention
The invention relates to a forgery/alteration protective material, particularly to improvement of a forgery/alteration protective material made information-readable under specified situations using a material with a low light transmittance.
2. Prior Art
A product produced by a specified enterprise is highly evaluated and is regarded as reliable by consumers if a brand name is attached thereto. Such a brand name stimulates the brand preference of consumers and even produces new added values.
However, taking advantage of the reliance and the preference of consumers, there exist some people who try to gain profit by falsely applying the brand name popular among consumers to the products. Forged products sold in markets by such people are often significantly inferior in the quality and accordingly ruin the reliability obtained with much effort among consumers and that is a serious problem for the enterprise.
Therefore, in order to avoid such a trouble, circulation of forged products has been tried to stop by adding technology for making forgery difficult and technology for distinguishing between intrinsic products and forged products.
As such a technology to be added to a product for the purpose to prevent forgery, there are technological means available using retroreflecting materials and multivariably discoloring pearl pigments. FIG. 14 shows a schematic illustration of a forgery protective material using a retroreflecting material.
As shown in the illustration, a forgery protective material 100 using a conventional retroreflecting material comprises a substrate 102, a retroreflecting material layer 104 and a transparent film layer 106 layered thereon and a photographic information 108 and/or letter information 110 by printing is inserted between the retroreflecting material layer 104 and the transparent film layer 106.
The illustrated retroreflecting material layer 104 is composed of a substrate 112, an interfering substance layer 114, and a transparent small spherical body 116. And under normal light such as sunray and illumination, light rays is irradiated from a variety of directions to the retroreflecting material, so that light scattering takes place in the respective layers and neither retroreflective light nor interference color by the interfering substance layer 114 is observed. And when light rays with a uniform proceeding direction (called as linear light) are irradiated, interfering color is observed owing to the retroreflection and the interference of light rays in the transparent small spherical body 116 and the interfering substance layer 114 and accordingly, distinction between an intrinsic product and a forged product is made possible by making letters and/or designed patterns, which differ under normal light irradiation and linear light irradiation, appear in the interfering substance layer.
If fabrication of the retroreflecting material 104 of a forgery protective material 100 is tried, the formation state of the substrate 112, the interfering substance layer 114, and the transparent small spherical body 116 composing the retroreflecting material layer is broken to make it difficult to re-construct the formation state, so that actually fabrication is to be considerably difficult. Further, it is extremely difficult to reproduce designed patterns and/or letters observed in the interfering substance layer 114 under normal light or linear light irradiation and that significantly contributes to forgery prevention.
However, in the case of a conventional forgery/alteration protective material with the constitution as shown in FIG. 14, it has been possible to fabricate the photographic information 108 and/or the letter information 110 by scratching the transparent film layer 106, falsifying the photographic information 108 and/or the letter information 110, and coating them with a transparent film just like before. Further, even if the photographic information 108 and/or the letter information 110 are altered, the retroreflecting material layer 104 still maintains the information and it makes judgment of the falsification extremely difficult. If the retroreflecting material layer 104 is obtained easily, forgery of such a conventional forgery/alteration protective material itself is easily done. Therefore, a conventional forgery/alteration protective material is inferior in security property in terms of processing of the top part of the material.